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MO: Fachverband Molekülphysik

MO 3: Chiral Molecules

MO 3.4: Vortrag

Montag, 9. März 2020, 15:00–15:15, f102

Spatio-temporally Resolved Probing of Chiral Near-Fields in an Electron Microscope — •Jan-Wilke Henke, Tyler Harvey, Ofer Kfir, and Claus Ropers — IV. Physical Institute: Solids and Nanostructures, University of Göttingen, Germany

Chirality, the lack of symmetry under spatial inversion, is central to many modern research topics, including the broken symmetry in biochemistry or magnetism. Insight into these phenomena can be gained by probing the optical response of the system with circular dichroism spectroscopy, which, however, has a limited spatial resolution. In scanning transmission electron microscopes, probes with a small spot size are routinely achieved, while the inelastic scattering of ultrashort electron pulses with the localised fields at the specimen (IELS) allows for the characterisation of the optical response [1,2].

In this presentation, we demonstrate the employment of IELS for probing chiral near-fields of a prototypical nanostructure. Similar to optical circular dichroism, a dichroic signal is obtained from the difference in coupling strength for incident illumination with left- or right-handed circularly polarised light. As the near-field is probed by femtosecond electron pulses [3], investigation of ultrafast phenomena is readily possible, while exploiting a wavelength-tunable pulsed light source enables recording dichroic spectra.

[1] B. Barwick et al., Nature 462 (2009)

[2] A. Feist et al., Nature 521 (2015)

[3] A. Feist et al, Ultramicroscopy 176 (2017)